Electrolytic refining of metals



- Patented July 7, 1925.

UNITED STATES FRANK F. COLGORD, OF NEW YORK, N. Y.,

REFINING & MINING COMPANY, OF MAINE.

No Drawing.

as will enable others skilled in the art to which it .appertains to make and use the same.

The invention relates to the electrodeposition of metals and more particularly to the electrolytic refining of metals such as lead,-

copper and tin.

It is the practice in electrolyt c refimng ,of metals to use so-called addition reagents in the electrolyte and the present invention is based on the discovery of a new reagent of this character whichmay be used with marked advantage over prior reagents in the electrodeposition or electrolytic refining of certain metals. This reagent is a sulfite liquor concentrate comprising the solid or viscous materials obtained from the waste sulfite liquors produced by treating certain woods with sulfite solutions. The evaporation of these liquors leaves a colloidal substance which may be designated as sulfite lignose. The principal constituents of this substance are or ma be lignin sulfuric acid, lignin sulfonic aci aldehyde sulfonic acids, furfural, and plant sugars. This substance is cheaply made from the waste sulfite liquors produced in the manufacture of paper pulp and is known under the trade names lignol and goulac.

I have discovered that sulfite lignose may be used as an addition reagent in certain acid electrolytes with remarkably advantageous results. It may be used to replace many of the addition reagents commonly used weight for weight and owing to its extremely low price, a substantial economy may be effected. It can be used alone or in partial replacement of some of the commonly used addition reagents effectin not only an economy thereby, but permitting the substitution to take lace in an old electrolyte and thus avoid t e cost of new electrolyte when changing over to this addition ELECTROLYTIC REFINING OF METALS.

PATENT OFFICEQ ASSIGNOB TO UNITED STATES SMhTING, PORTLAND, MAINE, A CORPORATION 0] Application filed August 28, 1924. Serial No. 734,798.

reagent. In many cases it produces .a cathode deposit superior to deposits obtained with other additional reagents, increasing 1 lation in the electrolyte of substances which might finally cause the deposit to form nonadherent and crystalline deposits has been noticed with this addition reagent, as in the case with some of the prior addition reagents commonly used.

The use of this addition reagent has given particularly excellent results in the electro lytic refining of lead with a fiuosilicate e ectrolyte. While the composition of the electrolyte can vary considerably without materially affecting the character of the deposit, excellent results have been obtained with an electrolyte containing 8.5 grams of lead as lead fiuosilicate per 100 c. c. and 4.2 grams of hydrofluosilicic acid per 100 c. c. The common addition reagent has been glue, but complete substitution of this new addition reagent can be effected. In actual practice this addition reagent when used alone is added daily to the electrolyte in the form of a water solution at the rate of one to two pounds of the dry reagent per ton of lead produced, while if used in conjunction with glue, the total quantity of the two reagents added daily is one to two pounds per ton of lead produced, with the glue and the new reagent varying in such proportion as desired. It may also be used in the electrol ic refining of lead using electrolytes of uosilicates and fluoborates or fluoborates alone. It may also be used in the electrolytic refining of lead using electrolytes of lead cresol-sulfonate, oo-ntainin for exanl ple, 80 grams of lead as Pb C,H .CH O .80 and approximately 70 grams of free cresol-sulfonic acid per liter sp. gr. equals 1.21; and also with electrolytes of mixed cresol-sulfonfil e and fiuosilicate electrolyte containingI 80 ams of lead as art lb(C,H,.C O .80 and as bSiF and approximately grams of free acid (estimated as H,SiF per liter sp. gr. equals 1.26.

Sulfite lignose, either alone or with glue, may be used as the addition reagent in the electrolytic refining of copper with sulphuric acid electrolytes. In this case the new reagent has a replacement valuefor glue of at least weight for weight. An additional benefit resulting from its use in the refining of copper is that the presence of a large amount of the reagent, or say an excess, has no detrimental effect which is not the case when using the common addition reagent glue in electrolytic copper relining. The new reagent also imparts a higher throwing power to the electrolyte and forms smooth, finely crystalline and tougher deposits than glue and nodules and dendritic crystals are restrained.

The new reagent may also be used in the electrolytic refining of tin with sulphuric, sulphuric and sodium sulfate, or fluosilicate electrolytes in conjunction with other addition reagents, especially replacing glue when used with other reagents. Single addition reagents have not been particularly successful in electrolytic tin refining and it has been the practice to use two or more addition reagents simultaneously, some of the addition reagents being glue, cresol, curacao aloes, and nicotine sulfite. Glue when used with either cresol, aloes or nicotine sulfatehas given in practice satisfactory deposits. The new reagent can however be substituted for glue in any of these combinations, efiecting thereby superior deposits in that they are less crystalline, more adherent and denser.

What is claimed is:

1. That improvement in the electrolytic deposition or refining of metals such as lead, copper or tin, with acid electrolytes which consists in the use in theacid electrolyte of .sulfite lignose as an addition reagent.

2. That improvement in the electrolytic deposition or refining of metals such as lead, copper or tin, which consists in the use as an addition reagent in the acid electrolyte of sulfite lignose in conjunction withglue or other addition reagents.

3. That improvement in the electrolytic deposition or refining of lead which consists in the electrodeposition of the lead from acid electrolytes containing sulfite lignose as an addition reagent.

4. That improvement in the electrolytic deposition or refining of lead with acid electrolytes such as fluosilicate, fluoborate or fluosilicate and fiuoborate electrolytes which consists in the use alone or in conjunction with other reagents of sulfite lignose as an addition. reagent.

5. That improvement in the electrolytic deposition or refining of copper with sulphuric acid electrolytes which consists in the use in the electrolyte of sulfite lignose as an addition reagent, either alone or in connection with other reagents.

.6. That improvement in the electrolytic deposition or refining of tin with acid electrolytes such as sulphuric, sulphuric and sodium sulfate, or fluosilicate electrolytes, which consists in the use in the electrolyte of sulfite lignose in connection with other addition reagents.

In testimony whereof I have signed my name to this specification.

FRANK F. OOLOORD. 

